I'm imagining that's the first meeting, the very first time Superman and Batman fully lay eyes on each other.

There's some sort of attack on the Gotham bridge, Superman flies in and starts to take out the baddies... and in the midst of the battle, through the various fire and smoke, notices some of the enemy combatants suddenly strung up by their ankles. His superhearing picks something up, he turns around... and boom, that image.